1. Field of the Invention
The present invention relates to a surface treating process, and in particular, a surface treating process for forming a deposited film of a metal such as aluminum, zinc and tin, or a metal nitride such as titanium nitride on the surface of a sintered product such as, for example, a rare earth metal-based magnet liable to be oxidized, and the like, thereby ensuring that the sintered product such as the rare earth metal-based magnet has an oxidation resistance.
In more particular, the present invention relates to a surface treating process capable of surface-treating a large number of works collectively and uniformly such as a sintered product, e.g., a rare earth metal-based magnet having a shape having an inside diameter portion such as a ring-like shape and the like, and to a surface-treating support member, a surface treating holder and a surface treating apparatus which are suitable for use in such process.
2. Description of the Related Art
For example, in a conventional surface treating process for a rare earth metal-based magnet, a vacuum vapor-deposition apparatus 120 as shown in FIG. 11 was used to carry out a vapor deposition of aluminum. In FIG. 11, reference character 121 designates a vacuum treating chamber which can be maintained at a predetermined degree of vacuum through a vacuum pump 122. In the vacuum treating chamber 121, aluminum 123, which is an evaporation source, is heated within an evaporation source holder 124 by a heater 125. A rare earth metal-based magnet article 130 as a work is accommodated in a cage-like container 126, and the vapor deposition of aluminum is carried out, while rotating the container 126, thereby uniformly depositing aluminum on the rare earth metal-based magnet article 130 as the work.
In the above conventional surface treating process, however, the substantially uniform vapor-deposition can be performed certainly. However, because the works are piled one on another within the cage-like container, it cannot be avoided that some deposition nonuniformity is produced. Therefore, it has been desired to propose a surface treating process by which a further uniform surface treatment can be performed. Many of rare earth metal-based magnet articles such as Nd--Fe--B based magnet articles, for example, resulting from the processing treatment, are rectangular parallelepiped, hard and moreover, have sharp corners. For this reason, the following problem is arisen: The corners collide with one another during the vapor deposition treatment, whereby the deposited film on the surface is peeled off and in a severe case, the corners of a product are chipped, resulting in a poor yield. Particularly, in a case of a large-sized article, there is a problem that the weight is large, and the collision energy is large, resulting in an extremely reduced yield. In a case of a work having an inside diameter portion and having a shape such as a ring-like shape and the like, there is a disadvantage that the inside diameter side of the work is occluded by the other work and for this reason, the uniform surface treatment of the inside diameter side cannot be achieved successfully.